The invention relates to a method of placing a single-capped electric lamp in a lampholder of a luminaire,
whereby the electric lamp provided with: a lamp cap having a metal shell with an axis, a first end which is closed by an electric insulator, and an open second end with an adjoining end zone, the metal shell having coupling devices outside the end zone for fixing the lamp cap in a lampholder; a light-transmitting lamp vessel with an electric element inside which is connected to contacts of the lamp cap by the conductors, which lamp vessel is fastened in the open second end of the shell,
is gripped by a tool,
is inserted with its lamp cap into the lampholder which cooperates with the coupling devices of the lamp cap, and
is fixed in the lampholder by rotation, the end zone remaining outside the lampholder thereby.
The invention also relates to an electric lamp suitable for use with the method and to a luminaire which is provided with the single-capped electric lamp.
Such a method is generally known. Wherever a large number of lamps are to be placed in holders, as in or for the motorcar industry, automated tools such as robots are used for this purpose. The lampholders may form part of, for example, lighting units which are to be placed at the rear of a car and which comprise lamps for the stop/rear light, reversing light, indicator light, fog rear light.
The tool grips the electric lamp by the lamp vessel or by the end zone of the metal shell.
The coupling device of the lamp cap may consist of screwthread, as is the case with Edison lamp caps. Alternatively, they may consist of projections, as is the case in the lamp according to U.S. Pat. No. 4,396,860, which has symmetrically arranged projections, or of asymmetrically arranged projections, for example, positioned at different heights. It is also possible that more than two projections are present as the coupling means, for example, at equal height but asymmetrically arranged according to Addition 50 610 to FR 853 358, or asymmetrically and at unequal heights according to JP 2-90483. Asymmetrical coupling means serve not only for coupling the lamp to the lampholder, but also as a key for rendering possible the coupling in one position only.
A disadvantage of the known method is that rejects frequently occur: lamp vessels break, for example, because they are gripped with excessive force or because the lamp is screwed home with excessive force; detaching of the lamp vessel from the lamp cap can also occur, during which electrical connections may also be broken; lamp caps are damaged, for example, because the surface of the end zone is scraped off or deformed. Damage of the lamp cap may result in a loss of corrosion resistance. A major disadvantage is that the lamp may suffer damage which is not immediately observable, but which nevertheless leads to early failure of the lamp.